The invention relates to a method of coating red-luminescing phosphor particles with hematite (.alpha.--Fe.sub.2 O.sub.3), whereby first Fe(OH).sub.3 is deposited on the phosphor particles and is subsequently convened into .alpha.--Fe.sub.2 O.sub.3 at a raised temperature. Such a method is known from JP 55-54 382(A) (English Abstract).